Transformation of iron oxides in oscillating redox and sulfidic conditions and its implications for phosphate immobilization in aquatic ecos

Excessive phosphorus (P) in surface water ecosystems is a primary cause of eutrophication, and chemical immobilization using Fe-rich materials is a commonly used approach to mitigate eutrophication due to their high affinity toward P. However, the long-term effect of Fe addition on P dynamics at the sediment-water interface is currently poorly understood, especially in environmentally relevant conditions. The objective of the proposed experiment is to determine Fe speciation of Fe amended lake sediments under fluctuating redox and sulfidic conditions with Fe K-edge bulk XAS. These data will allow us to determine how Fe speciation influences the biogeochemical cycle of P in the long term. This understanding is essential for assessing the effectiveness of Fe amendments as a sustainable strategy for improving water quality in rivers and lakes.

地表水生生态系统中过量的磷（P）是引发水体富营养化的主要诱因，利用富铁（Fe）材料开展化学固定因对磷具有高亲和性，成为缓解富营养化的常用手段。然而目前学界对铁添加后沉积物-水界面处磷的动态变化的长期影响仍缺乏深入认知，尤其是在环境相关的实际条件下。本拟开展实验的研究目标为：在波动氧化还原条件与含硫化物的环境中，采用铁K边整体X射线吸收光谱（X-ray Absorption Spectroscopy，XAS）分析添加铁的湖泊沉积物的铁的化学形态（Fe speciation），上述实验数据将帮助我们阐明铁的化学形态如何长期调控磷的生物地球化学循环，这一认知对于评估铁添加修复作为改善河湖水质的可持续策略的有效性至关重要。